Industrial Robots in Radiation Fields Herschel B. Smartt, Ph.D.

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Industrial Robots in Radiation FieldsHerschel
B. Smartt, Ph.D.

• July 1, 2004

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Industrial Robots in Radiation Fields

• What problem do we want to solve?
• Examples industrial robots
• Robot coordinate systems
• How do robots work?
• Degrees-of-freedom axes-of-motion
• Motors, encoders, resolvers, limit and home
  switches
• Radiation
• Radiation hardening
• Quick disconnects
• End effectors
• Robotics research

Slide 1
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Industrial Robots in Radiation Fields

• We want to use industrial robots to weld lids on
  certain radioactive waste materials storage
  canisters.
• We need to use robots because the radioactive
  exposure is too great in this specific
  application for personnel to be present.

Robot 1
Robot 1
Storage canister
Slide 2
4
Tool end
Articulated Arm Robot
6-axis motion
Floor mounted
Slide 3
5
Cartesian robots
Linear slides
Slide 4
6
SCARA robots
"Selective Compliant Assembly Robot Arm".
Slide 5
7
3 Translation axes
Y
P2
X
P1
Z
Slide 6
8
Y
P2
X
P1
Z
Slide 7
9
3 Translation axes 3 Rotation axes
Y
?2
P2
X
?1
P1
Z
?3
Slide 8
10
3 or 4 axis
6 axis
3 to 5 axis
Slide 9
11
Axis 6
6 degrees-of-freedom
Axis 4
Axis 3
Axis 5
Axis 2
Axis 1
Slide 10
12
?6
P
Forward kinematics for a specific robot
geometry, given ?1, ?2, ?3, ?4, ?5, ?6 find
P Inverse kinematics for a specific robot
geometry, given P find ?1, ?2, ?3, ?4, ?5, ?6
?4
?3
?5
?2
See, for example P. J. McKerrow, Introduction
to Robotics, Addison-Wesley, ISBN 0-201-18240-8,
1991. W. Khalil E. Dombre, Modeling,
Identification Control of Robots, Taylor
Francis, ISBN 1-56032-983-1, 2002.
?1
Slide 11
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Radiation environments
Robot exposure 10 to 1000 rem/hr gamma radiation
http//www.epa.gov/radiation/rert/radfacts.htm
Slide 12
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Motor 5
Motor 4
Motor 3
Motor 2
Motor 1
Slide 13
15
Servo motors and drives
Radiation hardened motors are available.
Slide 14
16
Optical encoders
Slide 15
17
Encoder disks
Plastic disk and sensing electronics are not
radiation hardened.
Absolute encoder disk
Incremental encoder disk
Slide 16
18
Encoder signals
Slide 17
19
Resolvers
Radiation hardened resolvers are available.
Slide 18
20
Internal drive by precision gear boxes and timing
belts
sprockets
Toothed belt
Radiation hardened timing belts are available.
Slide 19
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Tool quick disconnect collision detection
Slide 20
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Welding End Effector
Tool Quick Disconnect
Mounting Plate
Seam Tracker/Profile Measurement
Automatic Voltage Control Axis
Wire Feed Positioner
Oscillation Axis
Video Camera
Video Camera
Wire Guide
TIG Torch
Slide 21
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Video Camera

• Clear view of cold wire TIG process operating at
  350A
• View area of ¾1in. square at tip of tungsten
• Arc on and off viewing modes with commanded
  switching
• Camera position 4-7in. range from tip of tungsten
• Viewing angles 40-55deg from torch axis
• Minimum depth of focus of 1
• NTSC (color) or RS-170 (BW) video output
• Same camera system for leading and trailing
  cameras
• Standard environmental requirements

Slide 22
24
Video Camera
Camera Views
Leading Camera View
Trailing Camera View
Slide 23
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Video Camera

• Remote head camera system with out of cell CCU
• 2/3 Radiation tolerant CID imager
• 750 x 512 Imager pixels
• Resolution 450 TVL Horizontal, 400 TVL Vertical
• RS-170, 30FPS, 21 Interlaced Video Output
• 1x106 rad total exposure (at 7x105 rad/hr)
• 7x105 rad/hr maximum field strengths
• Less rad damage when device is not energized
• Camera Weight 9.7 oz

Slide 24
26
Slide 25
27
Slide 26
28
Robot welding cell 8-axis motion
Top linear slide
robot
Linear slide
Slide 27
29
robot
Weld torch
Linear slide
Slide 28
30
Drops of molten steel moving down the arc plasma.
electrode
molten steel drop
molten steel drop
weld pool
31
Weld torch
Spot weld
Slide 29
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wire feeder
power supply
operator
GUI
volume to wfs time
X-axis motor
arc length to voltage
Y-axis motor
Z-axis motor
Weld quality
Slide 30
bus
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Agent Block Diagram
dead man
tasks, state
analog
rules of behavior
com port
dead man
I
state
digital
Ethernet/TCP-IP
high level messages
serial port
mid-level motion control
Slide 31
34
wire feeder
power supply
operator
GUI
volume to wfs time
X-axis motor
arc length to voltage
Y-axis motor
Z-axis motor
Weld quality
Slide 32
35
Industrial Robots in Radiation Fields

• Discussed some aspects of using robots in
  radiation fields
• Looked at some various types of industrial robots
• Considered robot coordinate systems
• Examined some aspects of the internal technology
  of robots
• Considered problem of radiation hardening robots
• Discussed some research on agent-based robot
  control

Slide 33